The study found that although muscle-enhancing behaviors were more likely among teens who played on sports teams, steroid use was not.

Muscle-enhancing behaviors — including the use of steroids — is occurring among teenagers at a rate higher than previously believed, according to a new University of Minnesota study.

The findings, which were published online Monday in the journal Pediatrics, come from a 2010 survey of 2,793 teens attending 20 middle schools and high schools in Minneapolis and St. Paul.

Most disturbing was the finding that 5.9 percent of teenage boys and 4.6 percent of teenage girls have used steroids. Such drugs pose serious health problems, particularly for young people.

The study also found that more than 34 percent of the boys and 21 percent of girls have used protein powders or shakes to pump up their muscles. Such products, as Consumer Reports has pointed out, are of questionable value and may even pose health risks. Health experts are also concerned that teens may be using protein powders or shakes as substitutes for healthful foods.

Another 10.5 percent of the boys and 5.5 percent of the girls surveyed in the study said they used other controversial substances that claim to build muscles, such as human growth hormone and creatine.

The most common bulking-up behaviors used by teens in the study, however, were exercise and dietary changes. More than 60 percent of the teens reported that they had altered their eating habits to tone their muscles, and more than 90 percent of boys and 80 percent of girls said they exercised to build muscle bulk.

The findings about exercise and dietary changes may or may not reflect a healthy trend. “Although these may be beneficial,” the study’s authors point out, “compulsive or excessive use is cause for concern, because they may be a precursor to the development of more severe and unhealthy behaviors over time.”

Several surprises

Marla Eisenberg, the study’s lead author and an associate professor of pediatrics at the U of M, told MinnPost that some of the study’s findings were unexpected, such as the similarity between the muscle-enhancing behaviors of middle- and high-school students.

“I was also surprised that muscle-enhancing rates among girls were as high as they were,” she said. Bulking up is typically thought of as a boy’s concern, she explained.

Indeed, as Eisenberg and her colleagues point out in the study, recent research has found that boys’ dissatisfaction with their bodies has increased in recent decades — an increase that has occurred, not unsurprisingly, at a time when media images of physiques, including those used for children’s action figures, have become increasingly muscular.

But the media have also begun to portray the ideal women’s physique as being toned as well as thin — and that factor that may explain why more girls are now engaging in muscle-enhancing behaviors.

Doping scandals involving big-name athletes such as Lance Armstrong, Barry Bonds and Marion Jones may also be feeding the desire of teens — both boys and girls — to become more muscular, Eisenberg added. “The combination of those things,” she said, “really gives people a picture of a body they might want to achieve as well as some shortcuts for getting them there.”

No 'clusters' found

Interestingly, the study also found that although muscle-enhancing behaviors were more likely among teens who played on sports teams, steroid use was not. Nor did the study find any “clusters” of steroid use in specific schools.

“That really tells us that it seems to be going on across the culture,” said Eisenberg.

The survey used for this study is part of the U of M’s ongoing Project EAT, which has been asking Minnesota teens and their families in-depth questions about their dietary and other habits since the late 1990s. Participants come from widely diverse Twin Cities populations, both ethnically and economically.